Yes the wonderful thing about seasons 3-5 was the fact that there was an unbroken chain of goodness week in and week out with every episode for the most part being interesting. There wasn't a single episode in 4 or 5 I would drop--all were at least above average outings although I might find a way to splice together "Eggtown" and "The Other Woman"--another unanswered question who did Juliet remind Ben of according to Harper(she didn't make much of a splash did she)--his mom?
For season 3 I'd condense those first six episodes and drop Kate's "I Do", the John flashback one whose name escapes me with him as a pot grower and all that spiritual mumbo jumbo in a makeshift sweatlodge, Stranger in a Strangeland--very weeak Jack flashback, horrible with that trashy Asian chick and the horribly misleading promo for it that promised three of the show's biggest mysteries would finally be answered, the Kate/Juliet in the middle of season 3 was it "One of Us" where we learn Kate befriended Sawyer's partner--it was the first really average episode since the turnaround triggered with "Not in Portland", "Enter 77". Dump the stupid Chicken flashback one with Hurley--"Tricia Tanaka is Dead" or some such thing--I never remember the crappy episodes or their titles. YOu can tell I'm not a big Hurley fan.
Season two had a lot of crap so much so I can't even remember the names but "Dave" would be one, "Everyobody Hates Hugo", "Fire + Water" another--the Charlie goes bad episode--not even sure that freaky vision he had makes much sense even all these years later. Season one ditch "Whatever the Case Maybe" and the one that was mostly centered on golf.
Season 6--oh boy--the writers needed to take a cleaver to this year--the storytelling efficiency they so expertly demonstrated in the last 3 years was gone. I can't believe that if they wanted to stop with the mysteries they set up in the last 3 years and go for a straightforward adventure with alliances forging and dissolving repeatedly they couldn't have done so in fewer episodes instead of dragging them out. This season definitely did not need 18 episodes to tell this particular story. Focus on more interesting material and of course they had more than 18 episodes worth doing but they didn't. "What Kate Does"--goodbye. "Everybody Loves Hugo"-adios. "Happily Ever After" the first real episode with one main storyline instead of a whole bunch of jumping from subplot to subplot and it is booooooooring--instead of Heroes' "Company Man" or "Ab Aeterno" we got a very dull hour barring the exciting stuff with Widmore/Des in the present.